A while back I bought 2 emerald crabs and they have thrived in my bio cube. I looked in my tank today and found that the larger of the two has changed color to a dark black, its claws are huge and I can't figure out why? Is it a female or is it about to molt or is it the diet? Someone please advise.:unsure:

I've never seen them turn "dark black", but I'm wondering if it is about to molt.

Dave

sounds like it to me. i have seen them in green, brown, and even red ... but never black.

No black that I've seen with mine. My current Emerald crab looks whitish.

My emerald was black and HUGE after a few years. We killed him accidently when we moved the tank and .... umm... crushed him with a rock :-X

But he was black when we got him.